Ds has his second birthday in a few months time and I was thinking a trip to sea life aquarium might be a nice idea, perhaps a picnic beforehand. Dh wants to invite his family. He thinks we should pay for all their tickets if we invite them, I think we should invite them but make it clear in the invitation they have to pay for their own tickets if they want to come. With DH's parents, step parents, siblings and their partners it's about 9 people not including us or any my family (which would just be my parents).
Is it cheeky to say to DH's family they are welcome to come, no pressure but they have to pay for their own tickets? What's the best way to word it? Do I provide picnic food for everyone?